STEVENSON— INTERRELATIONS OF FOSSIL FUELS. 47 



in thickness. The interval between seams XI. and XII. in the 

 Fiinfkirchen area is from zero to 72 feet ; similar, though less 

 marked variations are recorded from other localities. Ordinarily, 

 the partings appear to be of freshwater origin, but occasionally one 

 contains marine forms of immediately offshore types. The char- 

 acter of the coal dift"ers greatly, many times, in the several benches ; 

 some yield excellent coal, but that from others is worthless ; that 

 from one bench may be caking, that from another may be non- 

 caking; that from one bench may be richly bituminous while that 

 from another may be almost anthracitic. Coal of Jurassic and 

 Triassic age is usually so far advanced in chemical change that iden- 

 tifiable plant structure seldom appears in the coal itself until after 

 treatment with Schultze's solution. But Grand'Eury states that, at 

 Nice, Equisetites is present in the coal, recognized by its form, 

 though all trace of structure had disappeared. The Keuper coals 

 of the Vosges contain bark and seeds, while Rhastic coal from 

 Bayreuth has many streaks which appear to consist wholly of 

 pollen exines. In the Rhastic of the Richmond field Equisetum is 

 abundant in coarse coal. But treatment with Schultze's solution 

 brings out evidence of vegetable tissue from all the coals examined. 

 The floor is as variable as the roof, being clay, shale or sand- 

 stone. Limestone is reported from only two localities described 

 in works consulted by the writer. Within several counties of Eng- 

 land the floor of the Lower Oolite coal or coaly shale is usually 

 clay or fine-grained more or less clayey sandstone and it contains 

 many roots, which, in at least one locality, clearly descend from the 

 overlying coaly shale. A calcareous floor in the Gausses of France 

 holds roots, which are well defined. Lipoid and his associates give 

 no details respecting the floors of Austrian coal seams but the 

 presence of plant remains is recorded incidentally for many locali- 

 ties. The presence of roots in floors is a famihar phenomenon in 

 the Lias of Hungary; in the Steierdorf-Anina district, they are 

 described as vertical, often branching, and they are associated with 

 plants of several types. According to Grand'Eury, roots, both 

 woody and herbaceous, are abundant in underclays and partings. 

 The condition is similar in the Fiinfkirchen area, where, according 

 to Gothan, the underclay proved to be a root-bed in every locality 



